Isolation, Identification, and Complete Genome Assembly of an Endophytic Bacillus velezensis YB-130, Potential Biocontrol Agent Against Fusarium graminearum.

Wen Xu,Runhong Sun,Lirong Yang,Mingcong Xia,Jie Zhang,Paul H Goodwin,Juan Liang,Chao Wu,Qi Wang,Liyong Zhang

doi:10.3389/fmicb.2020.598285

Abstract

Wheat scab caused by F. graminearum is a highly destructive disease that leads to yield reduction and mycotoxin contamination of grains. In this study, an endophytic bacterium of strain YB-130 was isolated from surface sterilized wheat spikes with scab symptoms and identified as Bacillus velezensis by whole genome annotation, 16S rRNA gene and average nucleotide identities analysis. The whole-genome sequence of strain YB-130 was obtained by PacBio sequencing. 88 putative Carbohydrate-Active Enzymes and 12 gene clusters encoding for secondary metabolites were identified in the YB-130 genome, including one gene cluster for the synthesis of lanthipeptide only found in strain YB-130 genome. In dual cultures, strain YB-130 significantly inhibited the growth of F. graminearum PH-1 and other eight fungal plant pathogens, indicating a broad antifungal activity. Furthermore, strain YB-130 was able to significantly inhibit spore morphology and hyphal development of F. graminearum PH-1. Strain YB-130 also reduced deoxynivalenol production by F. graminearum PH-1 in dual cultures, possibly due to its ability to suppress the expression of tri5, tri3, and tri8 that are required for deoxynivalenol production in F. graminearum. Overall, B. velezensis YB-130 is a promising biological control agent of both F. graminearum infection and mycotoxin production.

Highlights

Wheat (Triticum aestivum L.) is a major staple food crop for human and livestock worldwide (Shewry, 2009)
The genome sequence of strain YB-130 was sequenced, and genes for Carbohydrate-Active Enzymes (CAZymes) and secondary metabolites were identified. It exhibited strong antifungal activity against F. graminearum PH-1 and eight other fungal plant pathogens, and it reduced the production of deoxynivalenolYB-130 Against Fusarium graminearum (DON) by F. graminearum PH-1, which correlated with decreased expression levels of three DON synthesis-related genes, tri5, tri3 and tri8. These results indicated that B. velezensis YB-130 may be a potential biocontrol agent for controlling wheat scab disease and DON production caused by F. graminearum
Spores and hyphae of F. graminearum PH-1 were swollen in dual cultures with strain YB-130 compared to the control (Figures 1C–F)

Summary

Introduction

Wheat (Triticum aestivum L.) is a major staple food crop for human and livestock worldwide (Shewry, 2009). Wheat scab caused by F. graminearum is considered to be one of most devastating diseases of wheat worldwide, because it leads to severe yield losses and because infected grains contain harmful trichothecene mycotoxins, such as deoxynivalenol. YB-130 Against Fusarium graminearum (DON), that pose serious threats to food safety and human health (McMullen et al, 1997; Goswami and Kistler, 2006; Chen et al, 2019; Savary et al, 2019). During the past few decades, common approaches to controlling wheat scab have included the development of resistant cultivars and the use of chemical pesticides (Parry et al, 1995; Yuen and Schoneweis, 2007; Nelson et al, 2018; Pan et al, 2019). Biological control by microorganisms to suppress plant pathogens is an appealing alternative

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Conclusion